FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/tests/zfs-tests/cmd/threadsappend.c

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    
    /*
     * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
     * Use is subject to license terms.
     */
    
    /*
     * Copyright (c) 2013 by Delphix. All rights reserved.
     */
    
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <pthread.h>
    #include <string.h>
    #include <stdio.h>
    #include <unistd.h>
    #include <stdlib.h>
    #include <errno.h>
    
    /*
     * The size of the output file, "go.out", should be 80*8192*2 = 1310720
     *
     * $ cd /tmp; go; ls -l go.out
     * done.
     * -rwxr-xr-x   1 jdm   staff   1310720 Apr 13 19:45 go.out
     * $ cd /zfs; go; ls -l go.out
     * done.
     * -rwxr-xr-x   1 jdm   staff   663552 Apr 13 19:45 go.out
     *
     * The file on zfs is short as it does not appear that zfs is making the
     * implicit seek to EOF and the actual write atomic. From the SUSv3
     * interface spec, behavior is undefined if concurrent writes are performed
     * from multi-processes to a single file. So I don't know if this is a
     * standards violation, but I cannot find any such disclaimers in our
     * man pages. This issue came up at a customer site in another context, and
     * the suggestion was to open the file with O_APPEND, but that wouldn't
     * help with zfs(see 4977529). Also see bug# 5031301.
     */
    
    static int outfd = 0;
    
    static void *
    go(void *data)
    {
            int ret, i = 0, n = *(int *)data;
            char buf[8192] = {0};
            (void) memset(buf, n, sizeof (buf));
    
            for (i = 0; i < 80; i++) {
                    ret = write(outfd, buf, sizeof (buf));
                    if (ret != sizeof (buf))
                            perror("write");
            }
            return (NULL);
    }
    
    static void
    usage(void)
    {
            (void) fprintf(stderr,
                "usage: zfs_threadsappend <file name>\n");
            exit(1);
    }
    
    int
    main(int argc, char **argv)
    {
            pthread_t tid;
            int     ret = 0;
            long    ncpus = 0;
            int     i;
    
            if (argc != 2) {
                    usage();
            }
    
            ncpus = sysconf(_SC_NPROCESSORS_ONLN);
            if (ncpus < 0) {
                   (void) fprintf(stderr,
                       "Invalid return from sysconf(_SC_NPROCESSORS_ONLN)"
                       " : errno (decimal)=%d\n", errno);
                   exit(1);
           }
           if (ncpus < 2) {
                   (void) fprintf(stderr,
                       "Must execute this binary on a multi-processor system\n");
                   exit(1);
           }
   
           outfd = open(argv[optind++], O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777);
           if (outfd == -1) {
                   (void) fprintf(stderr,
                       "zfs_threadsappend: "
                       "open(%s, O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777)"
                       " failed\n", argv[optind]);
                   perror("open");
                   exit(1);
           }
   
           for (i = 0; i < 2; i++) {
                   ret = pthread_create(&tid, NULL, go, (void *)&i);
                   if (ret != 0) {
                           (void) fprintf(stderr,
                               "zfs_threadsappend: thr_create(#%d) "
                               "failed error=%d\n", i+1, ret);
                           exit(1);
                   }
           }
   
           while (pthread_join(tid, NULL) == 0)
                   continue;
   
           return (0);
   }

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